Research Tackles Effects of Dredging on Fish and River Habitats

May 24, 2011

Two Kansas State University professors are fishing for answers on how Kansas River dredging influences native wildlife and water resources.

Melinda Daniels, associate professor of geography, and Keith Gido, associate professor of biology, are collaborating on a project that involves habitat and fish sampling on the Kansas River, which stretches across northeast Kansas.

They are supported by a grant from the Kansas Department of Wildlife and Parks. The grant money comes from sales of state fishing and hunting licenses.

"These dollars go back to the people of Kansas because the research provides knowledge to help manage water resources throughout the state," said Daniels, who has received other funding and recognition for her research on conservation and restoration in the Kansas River basin.

Daniels is also collaborating with Craig Paukert, fisheries biologist and adjunct associate professor, on a project involving the Bowersock Dam, a hydropower dam on the Kansas River in Lawrence, Kan.

In both projects Daniels explores the non-living parts of river systems, such as water and sediment movement, while Gido and Paukert focus on fish populations. They evaluate all species of fish, with the projects' focus on rapidly declining native Kansas River fish species, such as the plains minnow, the silver chub and the shoal chub.

"These are fish that are found almost solely in Great Plains rivers," Daniels said. "If they drop out of Kansas, it is likely they would drop out pretty much everywhere."

Daniels is especially interested in the effects of dredging, which is the process of taking sand and gravel from the river bottom and pumping it up on the riverbanks. Dredged material is used in construction industries.

To help the Kansas Department of Wildlife and Parks understand how sediment removal influences the river, the researchers are looking at three active Kansas River dredge sites from Manhattan to Kansas City.

"KDWP is particularly worried about taking a lot of sediment out of the river because doing so in excess starts to cause riverbeds to cut down or incise," Daniels said. "That is a problem in the lower Kansas River in the Kansas City reaches, where water intakes have been left perched so they are no longer in the water. One of the questions we are trying to answer is how much of this bed incision may be due to sand and gravel mining."

To measure the effects of dredging, Daniels uses an acoustic Doppler instrument to detect the velocity of the water in the river and produce a map of the channel bottom topography. Because habitats and environments change seasonally, researchers map the river about once a month to understand how river flow and habitat change throughout the year.

The team has discovered that, on average, the Kansas River is about a meter and a half deep. But during certain times of year, when dredges are active, Daniels' team has detected holes as deep as 15 meters at active dredge locations.

"We're not prejudging whether dredging is a bad thing, but there is at least a temporary habitat alteration going on," she said. "We're trying to help generate information for the state agencies so that they can make decisions about how many dredges to permit, or if they should even continue permitting sand dredging."

At the Bowersock Dam in Lawrence the researchers are categorizing the surrounding habitat and observing differences in fish communities both upstream and downstream from the dam. They want to identify whether the dam is a barrier to fish movement, and if a fish passage structure in the dam would help reduce endangered species. Their findings can influence how dams are handled throughout the state.